Substances identified as Toxic Air
Contaminants, known to be emitted in California, with a full set of
health values reviewed by the Scientific Review Panel.

Click on a substance name to view its
fact sheet from the 1997 Toxic Air Contaminant
Identification List Summaries.
Please note some of the health values have changed since 1997.Click on the ++ to view its chemical
summary from the Office of Environmental Health Hazard
and Assessment website.

(There is a potential for 12 substances to move into this category after
the SRP has reviewed the noncancer chronic Reference Exposure Levels being developed under the Air Toxics "Hot
Spots" Program.)

Category IIa

Substances identified as Toxic Air Contaminants, known to be emitted in California, with one or more health values under development by the Office of Environmental Health Hazard Assessment for review by the Scientific Review Panel.

Click on a substance name to view its fact sheet from the 1997 Toxic Air Contaminant Identification List Summaries.
Please note some of the health values have changed since 1997. Click on the ++ to view its chemical summary from the Office of Environmental Health Hazard
and Assessment website.

Substances NOT identified as Toxic
Air Contaminants, known to be emitted in California, with one or more
health values under development by the Office of Environmental Health Hazard Assessment for
review by the Scientific Review Panel.

Click on a substance name to view its
fact sheet from the 1997 Toxic Air Contaminant
Identification List Summaries.
Please note some of the health values have changed since 1997.Click on the ++ to view its chemical
summary from the Office of Environmental Health Hazard
and Assessment website.

Substance identified as Toxic Air Contaminants,
and NOT KNOWN TO BE EMITTED from stationary source
facilities in California based on information from the AB 2588 Air Toxic "Hot Spots" Program
and the California Toxic Release Inventory.

Click on a substance name to view its
fact sheet from the 1997 Toxic Air Contaminant
Identification List Summaries.
Please note some of the health values have changed since 1997.

Substance

CAS
Number

Substance

CAS
Number

2-Acetylaminofluorene

53-96-3

3,3-Dimethyl Benzidine

119-93-7

4-Aminobiphenyl

92-67-1

Dimethyl Carbamoyl Chloride

79-44-7

Benzidine

92-87-5

2,4-Dinitrophenol

51-28-5

Benzotrichloride

98-07-7

2,4-Dinitrotoluene

121-14-2

Bromoform

75-25-2

1,2-Diphenylhydrazine

122-66-7

Calcium Cyanamide

156-62-7

Ethylene Imine (Aziridine)

151-56-4

Caprolactam

105-60-2

Heptachlor

76-44-8

Chloramben

133-90-4

Hexachlorobutadiene

87-68-3

Chlordane

57-74-9

Hexachlorocyclopentadiene

77-47-4

2-Chloroacetophenone

532-27-4

Hexamethylphosphoramide

680-31-9

Chloromethyl Methyl Ether

107-30-2

Methyl Iodide (Iodomethane)

74-88-4

Coke Oven Emissions

N/A

4-Nitrobiphenyl

92-93-3

O-Cresol

95-48-7

4-Nitrophenol

100-02-7

P-Cresol

106-44-5

N-Nitroso-N-Methylurea

684-93-5

DDE (P,P-Dichlorodiphenyldichloroethylene)

72-55-9

Parathion

56-38-2

Diazomethane

334-88-3

Beta-Propiolactone

57-57-8

1,2-Dibromo-3-Chloropropane

96-12-8

Quinoline

91-22-5

Dichloroethyl Ether (Bis(2-Chloroethyl)Ether)

111-44-4

Quinone

106-51-4

2,4-Toluene Diamine

95-80-7

N,N-Diethyl Aniline (N,N-Dimethyl Aniline)

121-69-7

O-Toluidine

95-53-4

Diethyl Sulfate

64-67-5

Toxaphene (Chlorinated Camphene)

8001-35-2

3,3-Dimethoxybenzidine

119-90-4

2,4,5-Trichlorophenol

95-95-4

4-Dimethyl Aminoazobenzene

60-11-7

Vinyl Bromide

593-60-2

Category
VI

Substances identified as Toxic Air
Contaminants, NOT KNOWN TO BE EMITTED from stationary source facilities in California, and are active ingredients in pesticides in California.

For futher information regarding the pesticidal uses of these compounds, please contact the Department of Pesticide Regulation

Click on a substance name to view its
fact sheet from the 1997 Toxic Air Contaminant
Identification List Summaries.
Please note some of the health values have changed since 1997.

Substance

CASNumber

Substance

CASNumber

+

Captan

133-06-2

+

Dichlorvos

62-73-7

+

Carbaryl

63-25-2

+

Methoxychlor

72-43-5

+

M-Cresol

108-39-4

+

Propoxur (Baygon)

114-26-1

+

2,4-D, Salts and Esters (2,4-Dichlorophenoxyacetic Acid)

94-75-7

+

Trifluralin

1582-09-8

Footnotes

*

Substances which have already been identified by the Air Resources Board as Toxic Air Contaminants through a comprehensive AB 1807 risk assessment and which have health values developed by the Office of Environmental
Health Hazard Assessment and approved by the Scientific Review Panel. A full risk assessment report is available.

To be listed as a Toxic Air Contaminant, these substances will go though
a comprehensive AB 1807
risk assessment.

++

Health value reviewed by the Scientific Review Panel.

X

Health value under development by the Office of Environmental Health Hazard
Assessment for review by the Scientific Review Panel.

0

These substances have been nominated for the development of additional health
values.

+

These substances are active ingredients in pesticides in California. For
further information regarding the
esticidal uses of these compounds, please contact the Department of Pesticide Regulation.

Note 1:

Substances in Category IIa and IIb without a draft or Scientific Review Panel reviewed Cancer Potency Value have been divided into 3 groups depending on their cancer classification by the U.S. Environmental Protection Agency (U.S. EPA) or the International Agency for Research on Cancer (IARC).

i

Classified by U.S. EPA and / or IARC as a probable or possible human carcinogen
(Group B1, B2, C, 2A, or 2B substances);

ii

Classified by U.S. EPA and / or IARC as insufficient/inadequate data exist
to classify
as to carcinogenicity to humans (Group 3 or D substances), or no data or value available
at this time;

iii

Considered not likely to be carcinogenic to humans by U.S. EPA and / or
IARC
(Group 4 or E substances).

Note 2:

The literature was reviewed for substances in Category IIa & IIb without
a draft or Scientific Review Panel reviewed Chronic Reference Exposure Level. "Limited data available"
was added to the row if some chronic toxicity data was found in the literature. "No data
available" was added to the row if no chronic toxicity data
was found in the literature.

Note 3:

The literature was reviewed for substances in Category IIa & IIb without
a draft or Scientific Review Panel reviewed Acute Reference Exposure Level. "Limited data available"
was added to the row if some acute toxicity data was found in the literature. "No data available"
was added to the row if no acute toxicity data
was found in the literature.

Note 4:

For all listings above which contain the word "compounds" and
for glycol ethers, the following applies:
Unless otherwise specified, these listings are defined as including any unique chemical substance
that contains the named chemical (i.e, antimony, arsenic, etc.) as part of that chemicalís infrastructure.

Note 5:

Chlorinated Dibenzo-P-Dioxins and Dibenzofurans:
The cancer potency value for
2,3,7,8-tetrachlorodibenzo-p-dioxin
was determined for the identification of chlorinated dioxins and
dibenzofurans as toxic air contaminants in 1986. At that time, the Board identified dibenzo-p-dioxins and
dibenzofurans chlorinated in the 2,3,7, and 8 positions and containing 4,5,6, or 7 chlorine atoms as toxic
air contaminants. Since 1986, International Toxicity Equivalency Factors (ITEFs) have been developed
which are used to evaluate the cancer risk due to exposure to samples containing mixtures of chlorinated
dibenzo-p-dioxins
and dibenzofurans. ITEFs are numerical factors that express the toxicity of an individual
chlorinated dibenzo-p-dioxin
or dibenzofuran relative to the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin.
ITEFs are listed for 16 chlorinated dibenzo-p-dioxins and dibenzofurans.

Note 6:

Diethanolamine: There
is a 1997 draft report by the National Toxicology Program that shows evidence of
carcinogenic activity in mice. (This may result in a change of the cancer classification.)

Inorganic Lead: Due
to information on non-cancer health effects showing no identified threshold, no
Reference Exposure Level has been developed. However, guidelines for assessing noncancer health
impacts are currently being developed by ARB staff.

Note 9:

Polycyclic Organic Matter:
Includes organic compounds with more than one benzene ring, and which
have a boiling point greater than or equal to 100 oC.

Note 10:

Benzo[a]pyrene: Potency
Equivalency Factors (PEF) have been developed for 24 polycyclic aromatic
hydrocarbons (PAHs). Using benzo[a]pyrene as a reference compound, a weighting scheme for PAHs
was developed in the 1994 Air Resources Board document entitled, Benzo[a]pyrene
as a Toxic Air
Contaminant. When a specific potency value is developed for a
chemical, it should be used in place
of the PEF.

Note 11:

Cyanide Compounds:
X'CN where X=H' or any other group where a formal dissociation may occur.
For example, KCN or Ca(CN)2...

Note 12:

Radionuclides: A type
of atom which spontaneously undergoes radioactive decay.

Environmental Tobacco Smoke:
An AB 1807-type of health assessment for Environmental Tobacco Smoke
was conducted by the Office of Environmental Health Hazard Assessment (OEHHA) and was approved by
the Scientific Review Panel on June 19, 1997. The Air Resources Board accepted the report from OEHHA
on October 23, 1997 and subsequently forwarded to the Department of Health Servicesí Tobacco Control
Program for appropriate action.

Note 15:

The OEHHA completed its inhalation cancer potency risk assessment on MTBE and the Scientific Review
Panel approved it at its November 1999 meeting.